Railway light signal



Dec. 26, 1933. B AN 3,940,916

I RAILWAY LIGHT SIGNAL Filed March 18, 1932 Fig. 2.

mvgzvrok BQPnaPd E. Oflayazz By @2270" w HIS ATTORNEY Patented Dec. 26, 1933 PATENKTOFFICE RAILWAY IGHT SIGNAL Bernard E. OHagan, Swissvale, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa,"- a corporation of Pennsylvania 7 v s I Application March 18, 1932. Serial No. 599,633"

8 Claims; (cl."z4c z19) My invention relates to apparatus for the control of {railway light signals, and has for an ob.-

ject' the provision of novel and improved means for automatically causing a light signal to give a more restrictive indication when traffic condi= tions warrant a less restrictive indication and the lamp or lamps which should give such less restrictive indication fail. I

I will describe two forms of apparatus embodying my invention, and will then point outthe novel features thereof in claims.

In theaccompanying drawing; Fig. 1 is a diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 is a view simi-' .15 larto'F'ig. 1, but showingja modification-of certain parts of the apparatus and also embodying my. invention.

Similar reference parts in each of the views.

'Referringf first toFig. 1, the reference charactersvH and D designate the usual home and jdistant relays respectivelyof arailway signaling system, and. the reference character Sdesignates a light signal controlled by these relays. This sigv.25 rial comprises three lamps G, Y, and R,.whi ch lamps, when lighted, indicate proceed, caution, and stop, respectively. In accordance with usual practice, the beam ,pr'ojected from lamp G may be green, the beam projected from lamp Y .may

be yellow, and the beam projected from lamp B may be red. The indication given by lamp G is less restrictive'than that given by either lamp Y or R,fand, the indication given .by lamp Y is less restrictive than that given by lamp R. h Lamp G is provided with a circuit which passes relay H, front contact 2-3 of relay D, and the lamp G toterminal O of the same source of current. Lamp Y is provided with a circuit which 40 includes front contact 19-? of relay H and back contact Z -eof relay D. 'Lamp R. is provided with a circuit which includes back contactv 1-8 of'relay H. ,It follows that when both relays H and D are energized, lamp G will be lighted; when relay H is energized and relay D deener gi'zed, lampY 'will 'beflightedf and when relay H is deenergiz'ed, lamp R will be lighted. The structure and operation or, the apparatus thus far described are in accordance with usual and standam practice, and willbe understood'without furcharacters refer to similar from terminal B, through front contact llof heat on a thermosensitivemember 9 of this device. The deviceC comprises a contact 9+-1 0,

which is normallyclosed but which opens in re-- sponse to the heat raysfrom lamp Gwhen this lamp is lighted. The device C also comprises two heating windings 11 and 12, either one of which, when energized, will serve to open contact 9 10,

Lamp Y is provided with an auxiliary circuitv which passeslfrom terminal B, through front contact 1,' '7' of relay H, frontcontact 2' 3rof relay D, contact 9 '10 of device C, and' the lamp Y to terminal 0. It follows that when both relays H and D are energized, and the contact 910of device .C is closed; lamp ,Ywill be lighted; t The heatingvvinding ll of dviceI'C is pro-' vided with a circuit which passesfrorn'terminal contact 56 of'relay D, and the winding "11 to terminal 0. It followsthat when the-caution lamp Y should be lighted; winding 11 will-be energized. Heating winding 12 is provided with a circuit which passes from terminalfB, through back contact 1--8 of relay H, and winding 12 to termihal'O. It follows that when the stop lamp B4 should be lighted, winding 12 will 'be energized. e I

The operation of the apparatusshown in Fig. 1 is as follows: As illustrated in this View, lamp G'is lighted becauseboth relays H and D are energized. "The thermosensitive device C is therefore receiving heat fromlamp G, so that con-' tact 9+10 is open. It follows that the auxiliary circuit for caution lamp'Y isopen at this contact.

Iwill now assum'etha't with the parts in the detail, I will assume that relay H is energized andrelay D deenergized, so that the caution lamp Y is, lighted. Heating ,winding llqwill' then be energizedso that contact 9'--10' of the thermosensitive device 0 will be open. If new relay D becomes energized, lamp G will become lighted but lamp Y willin'lnediately become extinguished, because its main circuit will be opened at contact 2 -4 of'r'elay D and its auxiliary circuit will be open at contact'9e-l0 of device C. Theparts are so proportionedthat. the heat from lamp .G

or fromstop to proceed; Toexplain this more in this lamp v is closed.

will become efiective to keep contact 9-10 open before this contact will close due to the deenergization of winding 11. In the absence of winding 11 under the conditions just set forth, lamps Y and G would be momentarily simultaneously lighted, because contact 910 would be closed while lamp Y is lighted, and this contact would not open until lamp G had been lighted long enough to heat the thermosensitive member 9 of the device C.

Similarly, if relay H is deenergized, so that lamp R is lighted, heating element 12 of device C Will also be energized. Then, if relays H and D become energized to supply current to lamp G,

contact 9-10 will be open and will not close during the transition period, so that there will be no momentary lighting of lamp Y.

Referring now to Fig. 2, the apparatus shown in this View is similar to that shown in Fig. 1-, except that the heating windings are omitted from the thermosensitive device C and the function of these windings is accomplished by a slow-releasing relay R having two separate windings 13 and 14, either one of which when energized will open the back contact 15 of this relay. The circuit for lamp (3, the main circuit for lamp Y, and the circuit. for lamp R are the same as in Fig. 1. The auxiliary circuit for lamp Y is from terminal B, through front contact 17 of relay H, front contact 2- -3 of relay D, contact 9-1O of the thermosensitive device C, back contact 15 of relay R, and. lamp. Y to terminal 0. Winding 13 of relay R is provided with. a circuit which includes front contact 1-7. of relay H and back contact 56 of relay D. This winding is. energized, therefore, when the caution lamp Y is lighted by virtue of its main circuit. Winding 14 of relay R is provided with a circuit which includes b ack contact 18 of relay H, so that this winding is. connected in multiple with the stop lampR and. is energized whenever the circuit for As illustrated in. Fig. 2 lamp G is lighted be- 7 cause. both relays. H and. D are energized. The

thermosensitive device C is therefore receiving heat from lamp G so. that the auxiliary circuit for lamp Y is open at contact 910 ofv this device. I will now assume that with the parts. in the conditions illustrated in Fig. 2 the lamp G burns out; Contact 910,will then close, and since relay R is deenergized, the auxiliary circuit for lampY will become lighted.

When relay H, is. energized and relay D isv deenergized, the. main circuit for the caution lamp Y willbe closed and relayR will be energized, because current will be supplied to its. winding 13. If now relay Dbecomes energized, lamp G will become lighted but the auxiliary circuit for lamp Y will not become closed, because this circuit will be kept open at back contact 15 of relay R until after contact 9-10 of the thermosensitive device 0 opens. Similarly, if 'relay H is deenergized so that the stop lamp R is lighted, relay R will. also be energized, because current will be supplied to-its winding 14. If now both relays H andD become energized, lamp G will become lighted, but the auxiliary circuit for lamp Y will not be closed because this circuit will be held open at back contact 15 of relay R until after contact 910 opens.

Although I'have herein shown and described only twoforms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope'of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a home relay and a distant relay, a light signal having a proceed lamp and a caution lamp, means for lighting said proceed lamp when both of said relays are energized, means for lighting said caution lamp when said home relay is energized and said distant relay is deenergized, and means including a thermosensitive device exposed to heat from said proceed lamp for causing said caution lamp to become lighted when both of said relays are energized if the proceed lamp is burned out.

2. A multiple aspect light signal for railroads having lamps controlled according to trafiic conditicns ahead, and automatic means independent of traffic conditions and involving a thermosensitive device responsive to the heat emitted by a less restrictive lamp for lighting a'more restrictive lamp if the less restrictive lamp fails and traffic conditions are such that the less restrictive lamp should be lighted.

3. A multiple aspect light signal for railroads having lamps controlled by trafiic conditions, ahead and giving yellow and. green, indications respectively, and automatic meansindependent of traffic conditions and involving av thermosensitive device exposed to heat emitted by the green lamp for lighting the yellow. lamp if thegreen lamp fails and traffic conditions are such that the green lamp'should be lighted.

i. In combination, a railway light signal, havan, auxiliary circuit for said second lamp including, said first controlling contact and the contact of said th'ermosensitive'device.

5. In combination, a railway light signal hav-' ing a lamp which when lighted gives a less re,-

strictive indication and'a second 'lamp which W when lighted'gives'a more restrictive indication, a thermosensltive device exposed to heat from said first lamp and having a normally closed contact which opens when the first lamp islighted; a circuit for said first lamp including a first controlling contact, a main circuit for said second lamp including a second controllingcontact, an auxiliary circuit for; said second lamp including said first controlling contact and a contact of said thermosensitive device, and means operating when the main circuit for said. second lamp is closed to supply heat tosaid thermosensitive device independently of said first lamp and to thereby keep the contact of said device open even though the first lamp is not lighted.

6. In combination, a railway light signal having a lamp which when lighted gives a less restrictive indication and a second lamp which when lighted gives a more restrictive indication, a thermosensitive device exposed to heat from said first lamp and having a normallyclosed contact which opens when the first lamp is lighted, a circuit for said first lamp including a first controlling contact, a main circuit for said second lamp including a second controlling contact, an. auxiliary circuit for said secondlamp including said first contact and the contact of said thermosensitive device, and means for preventing momentary simultaneous lighting of said two lamps when the main circuit for the second lamp becomes open" and the circuit for the first lamp becomes closed.

vice, two heating windings for, said thermosensitive device, means for energizing one of said heating windings when the main circuit for said caution lamp is closed, and means for energizing the other heating winding when the circuit to the stop lamp is closed. 8. In combination, arailway light signal-having proceed, 'cautionand stop lamps, a thermof sensitive device exposed to heat from the proceed lamp andhaving a normally closed contact which opens when the proceed lamp is lighted, a circuit for the proceed lamp, a main circuit for the caution lamp, and a circuit for the stop lamp, an

auxiliary slow-releasing relay having two wind-.

ings, an auxiliary circuit for the caution lamp including the contact of said thermosensitiveedevice and a back contact of said auxiliary relay,

means for energizing one Winding of .said auxiliary relay when the 'main circuit for the caution lamp is closed, and means for energizing the other winding of said auxiliary relay when the circuit for .said stoplamp is closed.

' I BERNARD E. OHAGAN. 

